{
    let list = new Set();
    list.add(5);
    list.add(7);
  
    console.log('size',list.size);
}

{
    let arr = [1,2,3,4,5];
    let list = new Set(arr);
  
    console.log('size',list.size);
}
{
    let list = new Set();
    list.add(1);
    list.add(2);
    list.add(1);
  
    console.log('list',list);
  
    let arr=[1,2,3,1,'2'];
    let list2=new Set(arr);
  
    console.log('unique',list2);
  }

  {
    let arr=['add','delete','clear','has'];
    let list=new Set(arr);
  
    console.log('has',list.has('add'));
    console.log('delete',list.delete('add'),list);
    list.clear();
    console.log('list',list);
  }


  {
    let arr=['add','delete','clear','has'];
    let list=new Set(arr);
  
    for(let key of list.keys()){
      console.log('keys',key);
    }
    for(let value of list.values()){
      console.log('value',value);
    }
    for(let [key,value] of list.entries()){
      console.log('entries',key,value);
    }
  
    list.forEach(function(item){console.log(item);})
  }
  
  {
    let weakList=new WeakSet();
  
    let arg={};
  
    weakList.add(arg);
  
    // weakList.add(2);
  
    console.log('weakList',weakList);
  }

  {
    let map = new Map();
    let arr=['123'];
  
    map.set(arr,456);
  
    console.log('map',map,map.get(arr));
  }

  {
    let map = new Map([['a',123],['b',456]]);
    console.log('map args',map);
    console.log('size',map.size);
    console.log('delete',map.delete('a'),map);
    console.log('clear',map.clear(),map);
  }
  